Manual therapy practitioners frequently include assessment of spinal joint mobility in their clinical examination and treatment of patients with low back pain. There is increasing evidence that clinical identification of spinal joint hypo- and hypermobility subgroups along with correspondingly tailored manual therapy treatment approaches can lead to more successful therapeutic outcomes. For example, individuals with low back pain and spinal hypomobility have been shown to respond better to spinal manipulation than those with spinal joint hypermobility. What underlying biological/neural mechanisms could be responsible for the different clinical responses from these subgroups when treated with spinal manipulation? This question motivates this career development plan which allows the candidate to accomplish his immediate goals of: a) working with an animal model that combines simulated spinal manipulation with peripheral neural recordings from lumbar paraspinal muscles and b) attaining knowledge of musculoskeletal biomechanics pertinent to the applied spinal loading that occurs during spinal manipulation through didactic coursework. In this study, an established cat lumbar spine model will be used to determine the effects of proximal, distal, and bi-segmental spinal joint hypo- and hypermobility on paraspinal muscle spindle discharge during simulated high velocity low amplitude spinal manipulation of different durations (25-400ms). Spinal joint hypomobility will be created by placing unilateral bone screws through the facet joint; hypermobility will be created via unilateral facetectomies. This study will reveal relationships between spinal joint dysfunction and sensory feedback related to a specific manual therapy intervention (spinal manipulation) with demonstrated effectiveness in the treatment of low back pain. By adding spinal joint hypo- and hypermobility conditions to an established animal model used to investigate spinal manipulation, this career development award provides the candidate with tools and experience to accomplish his long-term career goal of determining how spinal manipulation in the presence of spinal joint dysfunction affects the central nervous system. The candidate is a second generation chiropractor and this career development plan will be completed at the largest chiropractic research center in the world (Palmer Center for Chiropractic Research) which recently received a NIH/NCCAM grant to establish a four year multi-disciplinary Developmental Center for Clinical and Translational Science.